Field of the Invention
One disclosed aspect of the embodiments relates to a solid-state image pickup apparatus and an image pickup system using a solid-state image pickup apparatus, and more particularly, to a light shielding member of a solid-state image pickup apparatus having a charge storage unit disposed in each pixel.
Description of the Related Art
In an active pixel-type solid-state image pickup apparatus typified by a CMOS image sensor, it has been proposed to provide a global electronic shutter function.
The global electronic shutter function refers to a function of performing accumulation of a photo charge in a plurality of pixels arranged in a matrix such that the accumulation of the photo charge is started and ended simultaneously for all pixels. In the solid-state image pickup apparatus having the global electronic shutter function, each pixel includes a photoelectric conversion unit and a charge storage unit configured to store the charge generated via the photoelectric conversation for a particular period. In the charge storage unit of the solid-state image pickup apparatus having the global electronic shutter function, the charge is stored over a period from the end of the accumulation of the photo charge to the start of reading the charge. During this period, if an electric charge generated elsewhere other than the photoelectric conversion unit intrudes into the charge storage unit, noise occurs which may result in degradation in image quality. Japanese Patent Laid-Open No. 2008-004692 discloses a structure in which each pixel includes a photoelectric conversion unit and a charge storage unit, and a light shielding member is disposed over the charge storage unit.
In the structure disclosed in Japanese Patent Laid-Open No. 2008-004692, the light shielding member is disposed on an interlayer insulating film including a wiring layer. In this structure, oblique light may easily intrude into the charge storage unit via an opening of the light shielding member. In a case where a contact is disposed for use in supplying a voltage to an element, it is necessary that an opening for a plug of the contact is formed in the light shielding member. This makes it easier for oblique light to intrude into the charge storage unit. If the electric charge produced by such oblique light is mixed with an image charge stored in the charge storage unit, degradation in image quality occurs.
In view of the above, embodiments provide a solid-state image pickup apparatus having a charge storage unit with an improved light shielding performance, and an image pickup system using such a solid-state image pickup apparatus.